Pleuronichthys Cornutus Research Articles

트롤 어구에 부착된 쐐기형 해파리 분리배출장치의 성능 연구

In order to describe the performance of a wedge type jellyfish excluder device, a series of fishing experiments was carried out in the coastal areas of Yokji Island, southern Korea in 2009, using a trawl net with a cover net. The body size and weight of each individual (fish or jellyfish) caught in the experimental fishing were measured. In the case of giant jellyfish the bell diameter and weight were measured. The catch species was composed of giant jellyfish (Nemopilema nomurai), silver croaker (Pennahia argentata), yellow croaker (Larimichthys polyactics), finespotted flounder (Pleuronichthys cornutus), largehead hairtail (Trichiuruslepturus), melon seed (Psenopsisanomala) and so on. The weight ratio and individual ratio of total fish escaped through the outlet of the excluder device were 0.322 and 0.320, respectively. The weight ratios of giant jellyfish excluded from the trawl net ranged from 0.740 to 0.921 (average 0.852/haul). It means that the wedge type jellyfish excluder device performed well and allowed the most of the giant jellyfish to exclude through the trawl net. The approximately 70% of fish entered in trawl net was caught. The wedge type excluder device needs some improvements to minimize the fish escape from the trawl nets in the future.

사천바다목장해역 어류군집의 변동특성

Species composition and seasonal variation of fish assemblage in Sacheon marine ranching, Korea were examined. Sampling was seasonally made by a shrimp trawl from February 2009 to November 2009. A total of 55 species were collected. Of these, five species was dominant species comprising 51.1% of the total number of individuals. Nine species represented 57.3% of the total biomass. While total abundance (number of individuals) was high in spring, total biomass and species richness (number of species) and diversity were high in autumn. Cluster analysis, based on seasonally abundance data of the 21 most common species, showed that the species were separated into 4 different groups. Group A composed of Pholis nebulosa, Pleuronectes yokohamae, Hypodytes rubripinnis, Hexagrammos otakii, Tridentiger trigonocephalus and Paracercis sexfasciata, which were year round residents, group B Congr myriaster, Leiognathus nuchalis, and Platycephalus indicus, which were abundant in autumn, group C Sillago japonica, Pseudaesopia japonica, Zoarces gilli, Pholis fangi, and Pleuronichthys cornutus which were abundant in spring, and group D Sillago sihama, Cociella sp., Johnius grypotus, Cynoglossus joyneri, Cynoglossus robustus, and Pennahia argentata, which were abundant in summer. Principal component analysis revealed that seasonal variation in the fish assemblage was attributed to the abundance of temporal species such as conger and sand smelt fishes, which were abundant in summer, due to seasonal variation of water temperature.

Small subunit ribosomal RNA and mitochondrial cytochrome c oxidase subunit 1 gene sequences of 21 strains of the parasitic scuticociliate Miamiensis avidus (Ciliophora, Scuticociliatia)

The scuticociliate Miamiensis avidus is a histophagous parasite that causes high mortality in cultured marine fishes. Small subunit ribosomal RNA (SSU rRNA) and mitochondrial cytochrome c oxidase subunit 1 (cox1) genes were analyzed for 21 strains of M. avidus isolated from diseased olive flounder (Paralichthys olivaceus), ridged-eye flounder (Pleuronichthys cornutus), and spotted knifejaw (Oplegnathus fasciatus) in Korea and Japan (collected in 2003-2007). Analysis of SSU rRNA gene sequences (1,759 bp) indicates they are very conserved with less than 0.17% (3 nucleotides) differences suggesting that SSU rRNA are useful to identify M. avidus; however, the cox1 gene (900 bp) has higher variations with intraspecific divergences up to 5.67% (51 nucleotides). A distance tree of cox1 gene sequences based on a neighbor-joining analysis can separate 21 strains into five cox1 types (two heterogeneous clusters and three individual branches). The cox1-type matches with serotype of strains but do not reflect geographical origins, host species, or pathogenicity.

Age compositions of flatfish stocks as determined by a new otolithometric method, its application in the estimation of growth, spawning potential and fisheries management

We developed an ageing methodology and examined age composition of three flatfish stocks inhabiting the Seto Inland Sea, Japan. Ages were difficult to determine for three-lined tongue sole ( Cynoglossus abbreviates) and ridged-eye flounder ( Pleuronichthys cornutus) because the first year annulus ring was often indistinct; therefore, we used directional change in otolith growth to distinguish it. Sectioning and etching methods were powerful tools for identifying annual checks for red tongue sole ( Cynoglossus joyneri). Using these ageing methods, we determined age–length relationships and growth curves. The age composition of the populations studied and of the landings showed that a large proportion of the latter consisted of individuals under the mean age of sexual maturity, thereby reducing the percent spawning potential ratio (%SPR) to ≈ 20% for all species. These findings suggest that fishing pressure on immature fish is leading to overfishing of these flatfish stocks.

Antigenic differences of the scuticociliate Miamiensis avidus from Japan

In Japan and Korea, outbreaks of scuticociliatosis have frequently occurred in Japanese flounder, Paralichthys olivaceus. Morphological observations and small subunit rRNA gene sequences have shown that the causative agent of scuticociliatosis in the flounder is Miamiensis avidus (syn. Philasterides dicentrarchi). In this study, we elucidated the antigenic differences between six Japanese M. avidus isolates as an initial step toward developing an effective vaccine against the disease. Four Japanese flounder isolates (IyoI, Nakajima, JF05To and Mie0301 isolates), one spotted knifejaw, Oplegnathus punctatus, isolate (SK05Kyo), and one ridged-eye flounder, Pleuronichthys cornutus, isolate (RF05To) were subjected to serological analysis. Antisera against IyoI, SK05Kyo, Nakajima and Mie0301 isolates were raised in rabbits and used for immobilization assays and Western blotting. Immobilization assays showed that the six isolates could be divided into three groups, tentatively designated serotype I for IyoI, JF05To, RF05To, SK05Kyo, serotype II for Nakajima and serotype III for Mie0301. Western blotting results supported these three serotypes, with marked similarities in the banding profiles of IyoI, JF05To, RF05To and SK05Kyo isolates, which were distinct from the Nakajima and Mie0301 isolates. Three isolates, IyoI, Nakajima and Mie0301 that were selected as representatives of each serotype, were highly pathogenic to Japanese flounder by experimental infection. Based on these findings, we propose that there are at least three M. avidus serotypes in Japan.

Taxonomic review of East Asian Pleuronichthys (Pleuronectiformes: Pleuronectidae), with description of a new species

A review of East Asian frog flounders, genus Pleuronichthys (family Pleuronectidae), recognized Pleuronichthys japonicus sp. nov. and P. cornutus (Temminck and Schlegel 1846). Pleuronichthys japonicus sp. nov. is characterized by small, dark, rounded spots or marbled markings on the ocular side of the body, rounded cycloid scales somewhat irregularly arranged, usually 12 abdominal vertebrae, 67–80 (modally 75) dorsal-fin rays, 48–59 (modally 55) anal-fin rays, and a short branch of the supratemporal lateral line usually present on both sides. Pleuronichthys cornutus is characterized by densely distributed small, dark, irregular spots on the ocular side of the body, elongate cycloid scales somewhat regularly arranged, usually 13 abdominal vertebrae, 72–88 (modally 77) dorsal-fin rays, 52–65 (modally 58) anal-fin rays, and a branch of the supratemporal lateral line usually absent on both sides. Whereas P. cornutus is distributed from Miyagi Prefecture (Tohoku District) southward along the Pacific coast of Japan to the Bungo Channel, from Akita Prefecture (Tohoku District) southward along the Sea of Japan coast through the Tsushima Strait to the East China Sea, Yellow and Bohai Seas, the Taiwan Strait, and northern Chinese coast of the South China Sea, P. japonicus is distributed from southern Hokkaido southward along the Sea of Japan and Pacific coasts of Japan to the southern East China Sea. Geographic variations were found in caudal vertebrae and anal-fin ray counts, and caudal-peduncle depth in P. cornutus, and in ocular side body coloration, body depth, and head length in P. japonicus. Pleuronichthys lighti Wu 1929 was regarded as a junior synonym of P. cornutus.

트롤 탈출장치의 개발에 관한 연구

The aim of this study was to develop a trawl escapement device which can improve the survival rate of young fishes passed through trawl codend. The sea experiments according to the bar space of the device and bar materials were carried out to decide the bar space and device materials in Korean southern sea and off Cheju island. Stainless pipes and MC bars were used to test the efficiency of escapement device materials. Although escapement rates of MC bar for main species were a little higher compare with stainless pipe, the efficiency of device for stainless pipe was better than MC bar. Escapement devices of sort-K type and grid panel type were also compared. Escapement rates of redlip croaker(Pseudosciaena polyactis), blackthroat seaperch(Doederleinia berycoides) and finespotted flounder (Pleuronichthys cornutus) showed 61.7%, 2.0% and 2.7% on the sort-x type and 69.9%, 1.1% and 2.0% for the grid panel type but the difference was little. Fishes under 20mm head width and fishes which swimming speed is so slow compared with body length could not go through well the device. Escapement rates according to the bar space were estimated using grid panel type. The rates of redlip croaker(Pseudosciaena polyactis) for the bar space of 20mm, 25mm, 35mm were increased as 60.3%, 61.0% and 77.8%, and 9.8%, 16.4% and 45.6% for horse mackere1(Trachurus japonicus), respectively.

Accumulation of tributyltin in the blood of fish: Its application for monitoring in the marine environment

Accumulation of tributyltin (TBT) in serum, liver, muscle, and gill of olive flounder (Paralichthys olivaceus) was examined in a 30-d static-renewal exposure. Tributyltin accumulated rapidly in the serum of the olive flounder and to a greater extent than in the other tissues. The accumulated TBT concentrations in tissues were in the order of serum > gill > liver > muscle on a dry-weight basis. Tributyltin also was detected in the serum of feral fine-spotted flounder, Pleuronichthys cornutus, collected from the coastal area. The mean TBT concentration in serum (2,470 ng Sn/g) of the fine-spotted flounder was about 40 times higher than that in the liver (60 ng Sn/g) and 200 times higher than that in the muscle (27 ng Sn/g) on a dry-weight basis. The TBT concentrations in serum and sediment demonstrated a positive correlation. The percent TBT composition to total butyltin was much higher in the serum (71%) than in the other tissues and sediment (<47%). These results suggest that the analysis of fish blood serum could be a useful tool for monitoring exposure to TBT in the marine environment.

A method of determining selectivity curve of separator grid

This paper describes a theory and method for determining a grid selectivity curve from the data of a fishing experiment using a grid separator with several bar spacings. Grid selectivity is defined as the probability that a fish does not pass through a grid given that it has encountered the grid. Assuming that grid selectivity is regarded as a sieve process, grid selectivity, s g, can be expressed as a function of the ratio of cross-sectional diameter to bar spacing as follows: s g( d, L) = S g( R), where L and d are the cross-sectional diameter of the fish body and bar spacing of the grid, respectively, and R = L d . Application of the model is demonstrated by a fishing experiment using three grids with bar spacings of 8, 10 and 15 mm, carried out in a shrimp beam trawl in the Inland Sea of Japan. Grid selectivity was plotted against length by bar spacing, of two shrimp species (southern rough shrimp Trachypenaeus curvirostris and mantis shrimp Oratosquilla oratoria), two crab species (charybdid crab Charybdis bimaculata and portunid crab Portunus hastatoides), and frog flounder Pleuronichthys cornutus. The selectivity analysis in terms of the non-dimensional parameter R revealed that, for each species, a single selectivity curve describes accurately data of each of the grids as a master curve of grid selectivity. The master curve of grid selectivity allows estimation of the selectivity curve of grids other than those tested in this experiment.

Life history cycles of flatfish species in the Bohai Sea, China

This paper provides basic information on the general ecology and life history cycles of various flatfish species in the Bohai Sea, China. The species studied are Paralichthys olivaceus (Temminck & Schlegel), Cleisthenes herzensteini (Schmidt), Eopsetta grigorjewi (Herzenstein), Verasper variegatus (Temminck & Schlegel), Pleuronichthys cornutus (Temminck & Schlegel), Pseudopleuronectes yokohamae (Günther), Pseudopleuronectes herzensteini (Jordan & Snyder), Kareius bicoloratus (Basilewsky), Zebrias zebra (Bloch), Cynoglossus semilaevis Günther, Cynoglossus abbreviatus (Gray) and Cynoglossus joyneri Günther. Information on reproduction, eggs and larval distribution, growth and adult abundance is presented. Based on the biology and ecology of these flatfish, artificial enhancement of the commercial species in the Bohai Sea is discussed.

Food utilization of adult flatfishes co-occurring in the Bohai Sea of China

Stomach contents were examined of 4527 adult individuals of 12 flatfish species collected during the 1982–1983 Bohai Sea Fisheries Resources Investigation. Their food habits, diet diversity, similarity of prey taxa, trophic niche breadth and diet overlap were systematically analysed. Ninety-seven prey species belonging to the Coelenterata, Nemertinea, Polychaeta, Mollusca, Crustacea, Echinodermata, Hemichordata and fish were found and five of them were considered to be principal prey for flatfishes: Alpheus japonicus, Oratosquilla oratoria, Alpheus distinguendus, Loligo japonicus and Crangon affinis. Among the flatfishes, Paralichthys olivaceus was piscivorous, whereas Pseudopleuronectes yokohamae and Pseudopleuronectes herzensteini both had polychaetes and molluscs as their main prey groups. Pleuronichthys cornutus was classified as a polychaete-mollusc eater, with a strong preference for crustaceans. Verasper variegatus, Cynoglossus semilaevis, Eopsetta grigorjewi and Cleisthenes herzensteini ate crustaceans. Kareius bicoloratus was classified as a mollusc-crustacean eater. Cynoglossus abbreviatus, Cynoglossus joyneri and Zebrias zebra were grouped as crustacean-fish eaters. However, Z. zebra also took polychaetes and C. abbreviatus and C. joyneri preyed on some molluscs. Trophic relationships among the flatfishes were complicated, but they occupied distinctive microhabitats in different seasons and selected their specific prey items, which was favourable to the stability of the flatfish community in the Bohai Sea.

The biology of flatfish (Pleuronectinae) in the coastal waters of China

This paper summarizes the biology of flatfish (Pleuronectinae) in the coastal waters of China. Species composition, age, gonad maturation, feeding habit, growth, fecundity, distribution and migration are described. Flatfish are an important and abundant group of fishes in the coastal waters of China. 14 Species of 12 genera in the subfamily of Pleuronectinae have been recorded. Most species inhabit the cold waters of the Yellow Sea and its adjacent regions. The total annual catch varies over the years but on average amounts to several tens of thousands of tons, with a maximum of 80 000 tons. The commercially most important species are Kareius bicoloratus, Cleisthenes herzensteini, Eopsetta grigorijewi, Verasper variegatus, Pseudopleuronectes yokohamae, Clidoderma asperrima, Tanakius kitaharae, Pleuronichthys cornutus, Pseudopleuronectes herzensteini, Microstomus achne, a total of 10 species. For the most important species the population parameters are analysed.

周防灘産メイタガレイの資源管理方策の検討

At present, status of finespotted flounder Pleuronichthys cornutus stock in Suõ-Nada of Seto Inland Sea is considered to be on the decrease in comparison with the past. In this study, we reexamined for biological characteristics on stock assessment. We investigated the stock management scheme for this stock. As the results, present status of the flounder is overfishing. In conclusion, catch of yearling should be prohibited in small trawl fisheries in near future.

Artificial fertilization and spontaneous and hormone-induced spawning of the frog flounder, Pleuronichthys cornutus

Artificial fertilization and spontaneous and hormone-induced spawning of the frog flounder, Pleuronichthys cornutus

瀬戸内海東部海域のメイタガレイ同胞種の遺伝生化学的検出と形態学的検討

The occurrence of a sibling species of the frog flounder Pleuronichthys cornutus was uncovered by population analysis of allelic variations at three enzyme loci for 272 specimens of 8 population samples collected from the eastern part of the Seto Inland Sea. The sibling species (type B) was discovered in a population sample (WK) collected at the Kiisuido Channel, and highly resembled P. cornutus (type A) in morphological features, which is commonly distributed in this area. Type B, however, could clearly be distinguished by genotypes at Mdh-B and Icd-B loci, respectively, coding for malate dehydrogenase-B and isocitrate dehydrogenase-B. All the specimens of type B showed genotype B2B2 at Mdh-B locus and B3B3 at Ied-B locus. In the population sample WK, a remarkable homozygote excess was observed at these two loci, all the remaining specimens except the genotypes mentioned above were type A which had genotypes B1B1 at Mdh-B locus and B1B1 at Icd-B locus, and no heterozygotes were found at these loci. At another locus coding for α-glycerophosphate dehydrogenase, the same homozygote excess was demonstrated, and different alleles were predominant in types A and B. Morphological examination of the two types revealed that the number of dorsal, anal and ventral fin rays was fewer in type B than in type A, and the differences were statistically significant in most cases, but differences as to several other meristic characters and relative growth of body parts to body length were not significant. Differences in spots and coloration on the body surface and the possibility of isolation by a difference in spawning season between the two types are dis-cussed.

Studies of cysteine protease active in an acidic pH range of fish. I. Existence of cysteine proteinase active in an acidic pH range in fish.

The autolytic activity of various fish(16 species) muscle homogenate in an acidic pH range was measured in the presence of leupeptin and/or pepstatin A. The activity between pH 3 and 5 was inhibited by leupeptin as well as by pepstatin A in all fish examined. Especially, the activities of pointhead flounder Cleisthenes herzensteini, frog flounder Pleuronichthys cornutus, horse mackerel Trachurus japonicus and reticulated emperor Lethrinus semicinctus were inhibited chiefly by leupeptin The hemoglobin hydrolyzing activities of the crude extract from many fish muscles and livers in the presence of pepstatin A show the maximum activity at pH 4.0, and the activities of fish (53 species) muscles and livers in the presense of pepstatin A and/or leupeptin were measured at pH 4.0. The activities which was not inhibited by pepstatin A but inhibited by leupeptin were detected in almost all fish muscle and liver, and the activities of Pleuronectiformes (flathead flounder Hip-poglossoides dubius, frog flounder, pointhead flounder and bastard halibut Paralichthys olivaceus) were high. It was considered that the activity was due to the cysteine proteinase differing from cathepsin B or L.

周防灘産メイタガレイの成熟と産卵期

Studies on the maturity and spawning season as the biological parameters of finespotted flounder Pleuronichthys cornutus in Suo-Nada of Seto Inland Sea were not established yet. Based on the seasonal change of the maturity factor and results of the observation of gonads by the naked eye, evaluation of the degree of sexual maturity, main spawning season, body length and age at 50% sexual maturity were over 1.0 in both sexes, 11.0cm in females and 9.0cm in males respectively. Each age at 50% sexual maturity at age 0, 1, 2, 3 over 4 years was 70, 90, 100, 100% in females and 90, 95, 100, 100, 100% in males, respectively. Main spawning season was the beginning of November. The duration of maturity of male finespotted flounder is longer than that of female The beginning of the period of maturity of aged individuals was earlier than younger ones.

周防なだ産メイタガレイの年令と成長

For the studies of age and growth of finespotted flounder (Pleuronichthys cornutus, TEMMINCK et SCHLEGEL), age determination was carried out by counting the number of zones in the otolith from 12, 314 specimens caught in Suõ-nada area of Seto Inland Sea from October 1980 to October 1984.On the basis of the monthly changes of the appearance rate of hyaline zone at the margin of the otolith of 3, 268 specimens, hyaline zone is found once a year during the months from August to March, mainly December. The spawning season extends from November through December. Therefore, spawning roughly coincides in time with formation of hyaline zone, and the mean standard body length at the zone formation may be concluded as that at each full year of age.As the above mentioned results, each male and female finespotted flounder grows 109, 108mm in standard body length at one year of age, 131, 139mm in that at two years of age, 140, 154mm in that at three years of age, 146, 162mm in that at four years of age, and 149, 168mm in that at five years of age, respectively.No difference in growth of finespotted flounder is found between sexes until one year of age, however, female grows faster than male on and after one year of age.The age determination based on the otolith zones of finespotted flounder on and after five years of age is considerably difficult because of the difficulty of discrimination of opaque and hyaline zones in the otolith.

東京湾におけるメイタガレイ卵の分布生態について

Frog-flounder, Pleuronichthys cornutus, is one of the commercially important species among flat-fish taken from Tokyo Bay. The present report deals with seasonal and geographical distributions of eggs of the species in relation to the oceanography of the area. (1) The materials on which the present study is based are planktonic samples taken by the Tokai Regional Fisheries Research Laboratory and by Kanagawa Prefectural Fisheries Experimental Station during the period from 1957 to 1962 inclusive through the cooperative investigations on important neritic-pelagic fisheries resources. The samples were collected by vertical hauls of conical plankton-nets of 45cm or 60cm in mouth diameter. The nets were usually hauled from a depth of 150m or the ocean bottom when it was shallower than that up to the sea surface. (2) The eggs occur during the period from the late October till the early part of the following January. The peak appears during the period from the mid-November till the mid-December. The positive areas are the shallow zones on both east and west sides of the entrance of Tokyo Bay. None of eggs are found from the inner part of Tokyo Bay and Sagami Bay. (3) The ranges of temperature for occurrence are 16-21°C and those of chlorinity, 18-19‰. Thus, the positive area corresponds to the neritic zones where the water from the open sea does not strongly affect. The eggs are distributed neither in the low chlorinity region (inner part of Tokyo Bay) nor in the Sagami Bay which accepts the influence of open sea water directly. (4) The eggs of this species are spawned at around the entrance of Tokyo Bay. And this species grows in that area or after enterde into the bay, No commercial catch of this species is taken from the innermost part of the bay. There are two modes in the length composition of the summer catch from Tokyo bay, i. e. at around 16-20cm and 8-14cm in total length. These schools likely emigrate from the inside of the bay towards the entrance of the same in season of November-December. The larger fishes are considered to be mature there and become the spawners.

メイタガレイの卵発生と仔魚前期

Pleuronichthys cornutus (TEMMINCK et SCHLEGEL), the small turbot, is commonly distributed along the coast of Southern Japan and caught with much commercial importance. On December 6, 1963, the authors carried out the artificial insemination of this fish at Shimabara City, Kyushu, and observed the egg development and hatched larvae. The spawning season seems to extend from the middle of November to the end of December in Ariake Sound which the City faces. The egg is bouyant, colorless and spherical in shape, measuring 1.03-1.11mm in diameter. The egg has many small oil globules in early developmental stages, but the globules unite in from one to some large ones in gastrula stage. The egg-membrane has a hexagonal pattern of approximately equal size, measuring about 0.018mm across. The hatching took place in 115 hours at the water-temperature about 14.0°C. In the course of development, the embryonal body bears thickly melanophores and xanthophores. The newly hatched larva, measuring about 2.80mm in total length, had 12 ?? 13+24=36 ?? 37 myomeres (the vertebra-number 36-38). The anus opens at about the mid point of the body. The almost whole body is scattered with melanophores and xanthophores except the posterior part of the tail, where these chromatophores appear along the dorsal and ventral margins. The chromatophores appear thinly on the yolk sac. The 13 hours old larva is 3.69mm in total length, and its eyes are becoming black. The mouth opened at about 35 hours after the hatching. By 60 hours after the hatching the yolk was almost absorbed and the pectral fins appeared. The chromatophores of the head and the mid part of the body expand to the dorsal and ventral fin folds. Comparing this larva with the ones of Californian turbots of the same genus the following similar characters were found. 1) The anus opens almost mid part of the body.2) The chromatophores of the body are very thick, not forming cross band, and some ones expand to the fin fold.